Hi Our CIO has reached his send quota in Exchange 2007 of 500MB. I've gone into the EMC and increased this to 1GB. How long will this change take to take effect? Is it immediate? Also, we have Exchange servers around the globe. I made the change on his home Exchange server in London, but would it have made a difference if I had made it in Japan? Surely not because mailbox quota is not an AD attribute but an Exchange one?

It can take up to two hours (on top of the time for Active Directory to replicate the change to the AD site where his mailbox is.) See http://technet.microsoft.com/en-us/library/bb684892(EXCHG.80).aspx You can restart the Information Store service for it to take effect immediately but this will cause an outage for everyone else. You can adjust the registry values as described in the article, for future cases. Be aware of the performance implications though.